Riddell's Axiom could be breakthrough helmet for football
Pro Football Journal: Facemask Oddities
Seattle's Vicis raises $15M to expand work on protective football helmet
Pro Football Journal: Last Players To Not Wear Facemask
Pro Football Journal: Helmet Oddities
Pro Football Journal: My Favorite Facemask and a New Discovery
Pro Football Journal: My Favorite Facemask and a New Discovery
NFL prohibiting non-standard facemasks
Pro Football Journal: Facemask Oddities
The Otto Graham Myth and the Evolution of the Face Mask
Pro Football Journal: Facemask Oddities